A metal oxide semiconductor transistor is a field-effect transistor that can be widely used in an analog circuit and a digital circuit. For example, the metal oxide semiconductor transistor may include a gate electrode, a source electrode and a drain electrode, as well as an active layer. The gate electrode, the source electrode and the drain electrode are made of, for example, a metal material. After forming a channel region, for example, a step of forming a metal electrode is included. The metal electrode is prepared, for example, by wet etching, so when the metal electrode is formed, a metal etching liquid may corrode a semiconductor material between the source electrode and the drain electrode, so as to further affect product performance.